1. Field of the Invention
The present invention relates to a magnetoresistance element array composed of a plurality of arranged magnetoresistance elements.
2. Description of the Prior Art
A magnetic sensor for reading an information code (magnetic code) formed on a magnetic card is provided with a magnetoresistance element array.
For example, a magnetic sensor for reading a magnetic code in the magnetic dots which are arranged in a matrix of n rows.times.m lines on a magnetic card contains a magnetoresistance element array having the same number of magnetic detectors as the rows (n) or the lines (m). When the magnetic card passes by the magnetoresistance element array with a predetermined space therebetween in a predetermined direction, the magnetic sensor containing the magnetoresistance element array detects the information recorded on the magnetic card in the form of a magnetic code, and outputs as an electric signal to the output terminal.
Similarly, a sensor for reading magnetic codes formed on printed matter in magnetic ink such as bank notes is also provided with a magnetoresistance element array.
FIG. 1 shows a general structure of such kind of magnetoresistance element array. In FIG. 1, a stem 10 consisting of a rectangular box body is provided with a plurality of through holes 12 for receiving magnets at regular intervals in the longitudinal direction (the direction of Y in FIG. 1). A magnet 14 is inserted into each of the through holes 12 and fixed in the state in which the top portion of the magnet 14 protrudes toward the upper surface of the stem 10. To the center of the top portion of each magnet 14, an element substrate 18 of a magnetic detector 16 is secured by an adhesive or the like, and a first magnetoresistance element 20 and a second magnetoresistance element 22 are formed on the surface of the element substrate 18. Each of the first and second magnetoresistance elements 20 and 22 is composed of indium antimony or the like and the resistance value varies in accordance with the magnetic field applied thereto. Power source terminals 24 and 26 and output terminals 28 and 30 are provided for each of the magnetoresistance elements 20 and 22, respectively, and these terminals 24, 26, 28 and 30 are connected to pins 32, 34, 36 and 38, respectively, which are disposed in the vicinity of the magnet 14.
The connection of the magnetoresistance element array is shown in FIG. 2. The pins 32 and 34 are connected to the hot line and the cold line, respectively, of the power source. The other magnetic detectors 16 are connected to the power source in the same way. Thus, the magnetic detectors 16 are connected in parallel to each other with respect to the power source.
The pins 36 and 38 are connected to the output terminal. When a magnetic code recorded medium such as a magnetic card passes by the magnetic detector 16 in parallel thereto and with a predetermined space therebetween, the magnetic field produced by the magnet 14 is disturbed and the resistance value of the magnetoresistance elements 20 and 24 changes. The change in the resistance value is output to the output terminal as a detection signal through the pins 36 and 38. The required number of magnetic detectors 16 are provided and, hence, the magnetoresistance element array is provided with the same number of outputs.
In order to realize the connection shown in FIG. 2, a printed circuit board 39 shown in FIG. 3 is used. On the printed circuit board 39, printed conductors 40, 42 of a power source and a printed output terminal 44 are formed from a conductive material. The pin 32 is connected to the printed conductor 40 through the printed circuit board 39. Similarly, the pin 34 is connected to the printed conductor 42. To the output terminal 44, the pins 36 and 38 are connected. In this way, the power source terminal 24 of the first magnetoresistance element 20 is connected to the hot line of the power source, and the power source terminal 26 of the second magnetoresistance element 22 is connected to the cold line of the power source. Conduction is established on the output terminals 28, 30 of a pair of magnetoresistance elements 20, 22 of each channel by the output terminal 44 through the pins 36 and 38, respectively, and the output signal of each channel is taken out of the terminal 44 through a lead wire 46.
According to a conventional magnetoresistance element array having the above-described structure, when a magnetic card is passed by the surface side of the stem 10, for example, a read signal such as a magnetic code of each channel is lead to a signal processing unit of a computer or the like through the lead wire 46, thereby enabling a desired signal processing.
In such a conventional magnetoresistance element array, however, since the magnetic detector 14 is bonded to the top surface of the magnet 12 at the position estimated with the eye, it is difficult to bond the magnetic detector 16 to the center of the top portion of the magnet 14 at the right three-dimensional position. For example, it is difficult to prevent the magnetic detector 16 from deviating from the right position in the direction of Y which makes the spaces between the adjacent magnetic detectors 16 irregular, or in the direction of X, and the magnetic detector 16 from being disposed aslant. This inconvenience causes a trouble at the time of reading a magnetic code such as crosstalk between the adjacent channels and deviation in the reading timing in each channel. Thus, the conventional magnetoresistance element array has a problem in the reliability of reading.
In addition, since the above-described conventional magnetoresistance element array requires the printed circuit board 39 for connecting the magnetoresistance elements 20 and 22, and each of the terminals 24, 26, 28 and 30 of the magnetoresistance elements 20 and 22 is connected to the corresponding conductors of the printed circuit board 39 through the pins 32, 34, 36 and 38, respectively, these connecting operations become complicated, thereby lowering the operating efficiency. Since the printed circuit board 39 is necessary, the cost for the apparatus is raised and the size thereof must be enlarged disadvantageously.